1. Field of the Invention
The present invention relates to a gate valve, and more particularly, to a gate valve for a large-sized substrate and a substrate-treating apparatus including the gate valve.
2. Discussion of the Related Art
Apparatuses for a semiconductor device have been widely developed. In US patent application of publication No. US 2002/0024611, for example, a fabrication apparatus for a wafer having a diameter of 300 mm is disclosed. In the fabrication apparatus for a semiconductor device, a track for a transfer device is disposed in a central portion of a case, and a plurality of process stations are disposed along both sides of the track. The transfer device is supported by and moves along the track. In addition, a height of the transfer device is controllable, and the transfer device includes a substrate transfer means having a substrate holder. The substrate holder may be protruded to cross the track and use an arm assembly. The substrate transfer means is connected to the plurality of process stations having the wafer therein through the substrate holder.
The wafer is supplied to the transfer device from a transport box at front of the arm assembly. The fabrication apparatus is surrounded by a case, and the transport box is connected to the case. The transfer device is disposed among the plurality of process stations. Since a space surrounded by the case is isolated from the ambient air, the wafer transferred between the transfer device and the plurality of process stations is prevented from contamination.
However, a high vacuum for improving the isolation and contamination-preventing capacity of the case is limited by economical and structural conditions. The case has a structure whose an inner gas is slowly evacuated due to the pressure difference between the high vacuum space and the ambient air.
In addition, a possibility of transferring the substrate from the transport box to the space without contamination and a possibility of keeping a cleanness in the space while transferring the substrate through the transfer device are also limited. Specifically, the fabrication apparatus can not be applied to a large-sized substrate for a flat panel display (FPD). Since the large-sized substrate may have an area of a several square meters, the fabrication apparatus has an uncontrollable size. The fabrication apparatus for the large-sized substrate may have limitations in time and cost because it takes much time to obtain the high vacuum space for the large-sized substrate. Accordingly, the process time is lengthened and the fabrication cost increases.